Category Archives: BGP

EVPNs: The answer to your MPLS issues

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I had a good discussion with my Buddy JJ tonight on kind of the next step of network evolution for provider networks.  Many providers have evolved to MPLS networks with VPLS.  There are some inherent issues with this when it comes to things like bonding, MLAG, among other issues. Nothing is perfect, right?

So as we dive into What is EVPN I want you to know I am approaching this from a service provider standpoint. I also am no EVPN expert, but I am seeing it more and more as a solution to solve specific issues.  As a result, EVPN is sliding into a natural progression of the service provider network.

So what is EVPN?
There are folks much more versed on EVPN than I am. As a result, I will lean on some already written articles.
https://blog.ipspace.net/2018/05/what-is-evpn.html

https://www.cisco.com/c/en/us/products/ios-nx-os-software/ethernet-vpn.html#~stickynav=1

Components of EVPN
Now that you have a high-level overview of EVPN, what are some of the major components and features you should know? Let’s dive into that

Unified control plane.  EVPN can be used throughout your network.  You don’t have to use one stack for data center, one for metro to the data center, and yet another for connectivity between data centers. You can bring it all under one control roof so to speak.

EVPN, through BGP, marries the Layer 2 and Layer 3 layers together.  With MPLS everything is controlled at the layer3 level.  Now with EVPN Mac addresses become much more important. For example, Each EVPN MAC route announces the customer MAC address and the Ethernet segment associated with the port where the MAC was learned from and is associated MPLS label. This EVPN MPLS label is used later by remote PEs when sending traffic destined to the advertised MAC address. Pretty cool huh?

Image result for evpn service provider

As networks grow network engineers learn about things such as north-south traffic and east-west traffic.  Microsoft has a great article which explains this concept. https://blogs.technet.microsoft.com/tip_of_the_day/2016/06/29/tip-of-the-day-demystifying-software-defined-networking-terms-the-cloud-compass-sdn-data-flows/

East-West – East-West refers to traffic flows that occur between devices within a datacenter. During convergence for example, routers exchange table information to ensure they have the same information about the internetwork in which they operate. Another example are switches, which can exchange spanning-tree information to prevent network loops.

North | South – North- South refers to traffic flows into and out of the datacenter. Traffic entering the datacenter through perimeter network devices is said to be southbound. Traffic exiting via the perimeter network devices is said to be northbound.

So, if you are a growing Service provider look at EVPN.  In some upcoming articles, I will talk more about various components of EVPN and such.

 

Route Server Diagram for an IX

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Normally on a peering exchange, all connected parties will establish bilateral peering relationships with each other customer connected to the exchange. As the number of connected parties increases, it becomes increasingly more difficult to manage peering relationships with customers of the exchange.

However, by using route servers for peering relationships, the number of BGP sessions per router stays at two, if the IX has deployed redundant servers.

A secure BGP routing infrastructure using RPKI

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How does BGP select routes?

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Printing Mikrotik BGP received routes

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Another BGP blunder.but not THAT one

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Recently, there has been much talk about the Cloudflare BGP blunder and others. The Network Collective even did a video about such things. But did you know there was one involving the entire /12 of IPV6 space? Airtel AS9498 announced the entire IPv6 block 2400::/12 for a week and no-one noticed. Someone typed a /12 instead of a /127.

So why did no one notice? I think part of it is due to the low usage of v6 space.  Sure, all kinds of people claim stats on IPV6 usage.  They talk about X number of traffic is v6, etc. There is a difference between users and connections.  A connection may not actually represent unique users.

Secondly, people are used to IPV6 being buggy.  I know many ISPs who disabled v6 as part of their troubleshooting steps.

I know there will be several folks who jump all over me about IPV6 being the wave of the future and we all should be using it.  Yes, we should, but there is no huge hurry when it comes to business cases.

“Glue addresses” in networking

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Imagine this scenario.  You have bought an IP or DIA circuit from someone that is going to provide your network with bandwidth.  Typically this company will make the connection, IP wise, over a /30 or even a /29 of IP space.  I have called this the “glue address” for many years.  This is the IP address that binds (the glue reference) you to the other provider’s network. They can route you IP blocks over that glue address or you can establish BGP across it, but it is the static address which binds the two networks together.

Some network folks call this a peering address.  This isn’t wrong but can infer you are doing BGP peering across the address.  You aren’t always doing BGP across the glue address.

#routinglight #packetsdownrange

Noction: BGP in Large Networks

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Are you running a large scale BGP network? Need some tips and help on what to optimize and what your next steps to optimize your setup?

Using iBGP with loopback addresses
Making sure all routers know next hop and loopback addresses
Whether to use route reflectors rather than an iBGP full mesh
Where to originate prefixes
Where and how to filter announcements

Using BGP in large scale networks and how to get the most out of it. Paper by Noction

BGP Monitoring RFC 7854

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https://tools.ietf.org/html/rfc7854

   This document defines the BGP Monitoring Protocol (BMP), which can be
   used to monitor BGP sessions.  BMP is intended to provide a
   convenient interface for obtaining route views.  Prior to the
   introduction of BMP, screen scraping was the most commonly used
   approach to obtaining such views.  The design goals are to keep BMP
   simple, useful, easily implemented, and minimally service affecting.
   BMP is not suitable for use as a routing protocol.